Let it go!
There is no point crying over a spilled milk. Let it go!
There is no point agitating over things you cannot change. Let it go!
Things happen to us in life that we don't have the power to influence. let it go!
There are times you are duped and cheated by the people you trust the most and you are let down by trusted allies. Let it go!
The best to get fron the past bitter experiences is to learn from them and move on with life. Check where your downfalls are and examine the loopholes on your ends.
Then device new strategies and regroup. Refire and come out strong from the situation. You might be let down but never stay on down with your back on the ground. Let it go and move on!